Mistral Small 3.1 and GPT-5 Pro don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. Mistral Small 3.1 shipped 143 days before GPT-5 Pro, so benchmark comparisons should account for the intervening progress.

Mistral Small 3.1 is open weight, while GPT-5 Pro is proprietary.

Direct benchmark comparisons are unavailable — Mistral Small 3.1 and GPT-5 Pro don't publish scores on any of the same benchmarks.